Background

Although unsettled behaviour is a common problem in the first months of life, families complain that they receive conflicting advice from health professionals. A simplistic, biomedical approach may cause harm, because only 5% of unsettled babies have organic disturbance. However, an approach that focuses on psychosocial support may fail to diagnose correctable clinical problems, including feeding difficulty, which paradoxically risks entrenching parental anxiety and disrupted mother–child relations long term.

Applied complexity science frames the mother and baby as a complex adaptive system (CAS), made up of multiple known and unknown dynamically interacting and co-evolving factors out of which cry-fuss behaviours emerge, and demands a transdisciplinary integration of evidence.

Applied complexity science makes sense of the puzzling non-linear interrelationships observed between cry-fuss problems and various factors, including aversive feeding behaviours, or perinatal anxiety and depression.

The CAS of the mother and baby self-organises according to inherent patterns determined by a long evolutionary history, emphasising the importance of supporting parents' trust in, and attunement with, their unsettled baby's innate capacity for self-regulation in the first months of life. The CAS of the mother and baby displays sensitivity to initial conditions, so that a small change early on may have unpredictable and disproportionate effects after an unpredictable time lag, emphasising the importance of early intervention once unsettledness emerges. …